Molecular Defects of Insulin Signaling in PCOS

描述(申请人提供)：多囊卵巢综合征(PCOS)影响约4%的育龄妇女，是少排卵性不孕症最常见的原因之一。50%到70%患有多囊卵巢综合征的女性表现出胰岛素抵抗，与体重无关，由此产生的代偿性高胰岛素血症导致这种疾病的高雄激素性特征。总体而言，对多囊卵巢综合征胰岛素信号缺陷的分子方面知之甚少。先前的研究表明，胰岛素刺激的葡萄糖转运不足，表明PI-3激酶/Akt/GLUT-4级联反应发生了变化。或者，在这些患者的成纤维细胞中，对胰岛素反应的有丝分裂活性似乎是正常的，这表明MAPK途径在多囊卵巢综合征中可能没有受到影响。基于这些观察，我们假设脂肪组织中的胰岛素受体(IR)信号异常是PCOS女性中一种常见的异常；该缺陷存在于IR下游，影响PI-3激酶/Akt/Glut-4途径，但不影响MAPK途径。我们还假设，PCOS的胰岛素抵抗可能与内脏(大网膜)异常的关系比皮下脂肪更密切。 我们的具体目的是确定PCOS患者的脂肪细胞中是否存在异常的IR信号。具体地说，我们将通过研究10名正常体重或肥胖前期的PCOS患者和10名年龄/种族/身体质量匹配的对照组的腹部皮下和大网膜脂肪组织来验证我们的假设。在这些组织中，我们将确定：i)IR、IR底物-1和2蛋白(IRS-1/2)、关键中间蛋白(即PI-3激酶/Akt级联的Akt、GSK-3和FKHR；Erki/2级联的c-Raf、MEK-1、Erki/2和p90RSK；SAPK/JNK级联的JNK；以及同名级联的p38MAPK)和翻译调节因子p70 S6的胰岛素反应的总量和程度；和ii)GLUT-4和IRS相关的PI-3激酶的总量。 我们应该注意到，在研究PCOS中潜在的胰岛素抵抗机制的早期阶段，这种研究胰岛素信号的系统方法是至关重要的。从长远来看，这些研究有可能最终阐明部分或大多数患者的病因机制(S)，帮助开发有针对性的治疗方法，并指导寻找多囊卵巢综合征的分子标志物。

DESCRIPTION (provided by applicant): The polycystic ovary syndrome (PCOS) affects about 4% of reproductive-aged women, and is one of the most common causes of oligo-ovulatory infertility. Between 50% and 70% of women with PCOS demonstrate insulin resistance, independent of body weight, and the resulting compensatory hyperinsulinemia leads to the hyperandrogenic features of the disorder. Overall, little is know about the molecular aspects of the insulin signaling defects of PCOS. Previous studies have indicated that insulin-stimulated glucose transport is deficient, suggesting an alteration along the PI-3 kinase/Akt/GLUT-4 cascade. Alternatively, mitogenic activity in response to insulin appears to be normal in the fibroblasts of these patients, suggesting that the MAPK pathway may be unaffected in PCOS. Based on these observations we have hypothesized that abnormal insulin receptor (IR) signaling in adipose tissues is a frequent abnormality in women with PCOS; and that the defect is present downstream from the IR, affecting the PI-3 kinase/Akt/GLUT-4, but not the MAPK, pathway. We have also hypothesized that the insulin resistance of PCOS may be more closely related to abnormalities of visceral (omental) than subcutaneous fat. Our Specific Aim is to determine whether abnormal IR signaling is present in the adipocytes of patients with PCOS. Specifically, we will test our hypothesis by studying the abdominal subcutaneous and omental adipose tissues of 10 normal-weight or pre-obese PCOS patients and 10 age/race/body massmatched controls. In these tissues we will determine: i) the total amount and the degree of phosphorylation in response to insulin of the IR, the IR substrate-1 and 2 proteins (IRS-1/2), and of critical intermediate proteins (i.e., Akt, GSK-3, and FKHR of the PI-3 kinase/Akt cascade; c-Raf, MEK-1, ERKI/2, and p90RSK of the ERKI/2 cascade; JNK of the SAPK/JNK cascade; and p38 MAPK of the cascade of the same name) and the translational regulator p70 S6; and ii) the total amounts of GLUT-4 and IRS-associated PI-3 kinase. We should note that this systematic approach to investigating insulin signaling is critical at this early stage in the study of the mechanisms underlying insulin resistance in PCOS. Long term, these studies have the potential of eventually elucidating the etiologic mechanism(s) in some, or most, patients; helping to develop targeted therapies; and guiding the search for molecular markers for PCOS.